Certain Localities DEMAND it Or the use of weather protection paint like several coats of RED LEAD plus finish coat. Or Coal Tar enamel hot applied with a 15# felt covering. The main reason most plumbers dont use galvanized pipe is it cost more and the reaon some plumbing officals dony like Galvanized fittings is they are scared once the zinc coating peels off it can expose a casting inperfection and thus a leak.
Check local codes and your gas supplier to make sure the gas will not effect the zinc coating inside the pipe. [Edited by SylvanLMP on 14 December 2000]